1. Field of the Invention
The present invention relates to light emitting devices and more particularly to a light emitting device which has planar light emitting element regions formed on a transparent substrate.
The present application claims priority from Japanese Patent Application No. 2002-223250, the disclosure of which is incorporated herein by reference for all purposes.
2. Description of the Related Art
Among light emitting devices used as display devices or the like, a variety of light emitting devices have been suggested which have a planar light emitting element region formed in a predetermined area on a transparent substrate to emit light through the transparent substrate. Such a light emitting device has a light emitting element region formed at each region for transmitting light out therethrough (light transmitting region) on the transparent substrate, and is provided with a plurality of light transmitting regions formed as required on the transparent substrate (see Japanese Patent Laid-Open Publications No. 2001-265270 and No. 2001-267084).
By way of example, FIG. 1 illustrates a conventional light emitting device. The light emitting device has a transparent substrate 1, such as a glass substrate or a transparent plastic substrate, on which successively deposited are the following layers. That is, the layers include a transparent electrode layer 2 (first electrode layer) which is formed of ITO film or the like and serves as the anode, an insulative layer 4 formed on the transparent electrode layer 2, an organic light emissive layer 5 made of a predetermined organic material, and a metallic electrode layer 6 (second electrode layer) which is formed of Al or the like and serves as the cathode. With this configuration, a voltage is applied between the transparent electrode layer 2 and the metallic electrode layer 6 to cause the organic light emissive layer 5 disposed between these electrode layers to emit light, which is in turn transmitted out through the transparent substrate.
In this light emitting device, its display portion is divided into two parts: the first to fourth display portions A–D and a supplementary display portion E, all of which are arranged in a longitudinal direction of the transparent substrate. To form each of the display portions, the transparent electrode layer 2 having display patterns (display pattern portions 2A–2E) are patterned on the transparent substrate 1. These display pattern portions 2A–2E are individually connected to a leadframe (not shown), provided on an edge of the transparent substrate 1, via wiring portions (not shown) formed with the transparent electrode layer 2.
The insulative layer 4 is formed to cover the aforementioned wiring portions except for the display pattern portions 2A–2E on the transparent electrode layer 2. This insulative layer 4 prevents a voltage from being applied to the organic light emissive layer 5 at the portion corresponding to the aforementioned wiring portions, thereby preventing light emission from this portion. The organic light emissive layer 5 is formed so as to cover the display pattern portions 2A–2E on the entire surface of the transparent substrate 1 including the insulative layer 4, with the metallic electrode layer 6 being further formed on the entire surface thereof.
The light emitting device having such a configuration is intended to provide improved functionality or design for the light emitting device by forming a plurality of display portions on a single substrate.
According to such a conventional light emitting device, the light emitting element region including the first electrode layer, the light emissive layer, and the second electrode layer is formed at each light transmitting region on the surface of the transparent substrate. With this configuration, to provide a light emission in a form required, it is necessary to pattern transparent electrode layers or the like in accordance with the requirements thereof, thereby causing an increase in complication of the fabrication process.
Additionally, since the lead frame or the like is formed in the light emitting device, it is difficult to form a light emitting element region near an edge of the transparent substrate in the conventional light emitting device. This makes it impossible to form a light transmitting region near the edge of the transparent substrate, thereby presenting a problem that an effective use cannot be made of the entire surface of the transparent substrate as a light transmitting region.
Furthermore, among light beams emitted from the light emitting element region formed on the transparent substrate, a light beam which is generally perpendicularly incident on the transparent substrate can be transmitted out through the transparent substrate. However, those light beams which are incident upon the transparent substrate at some angles are not to be transmitted out from the light transmitting region of the transparent substrate, thereby presenting another problem that full use cannot be effectively made of the light emitted from the light emitting element region.